CO Steam & Hot Water Heating
Contractor Exam Questions and Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant Download
Pdf
In a hydronic hot-water heating system, what is the primary function of
the expansion tank?
A. Increase boiler pressure
B. Remove dissolved oxygen
C. Absorb the increase in water volume as the water is heated
D. Increase circulation velocity
Rationale: Water expands as its temperature rises. The expansion
tank provides a compressible air or gas cushion that accommodates
this increased volume and helps prevent excessive system pressure.
, 2. What is the primary purpose of a pressure-relief valve on a
hydronic heating boiler?
A. Control the thermostat
B. Prevent low-water conditions
C. Regulate pump speed
D. Protect the boiler and piping from excessive pressure
Rationale: A pressure-relief valve is a safety device that opens
automatically when system pressure reaches its set point. This
prevents excessive pressure from damaging the boiler, piping, or other
components.
3. In a closed hot-water heating system, what component is
commonly used to maintain the minimum required system
pressure?
A. Air separator
B. Pressure-reducing fill valve
C. Circulator
D. Check valve
Rationale: A pressure-reducing fill valve automatically admits water
from the supply when system pressure falls below its regulated
setting. It helps maintain adequate pressure throughout the heating
system.
, 4. What is the main purpose of an air separator in a hydronic heating
system?
A. Increase boiler temperature
B. Reduce water pressure
C. Remove entrained air from the circulating water
D. Prevent thermal expansion
Rationale: Air in a hydronic system can cause noise, corrosion, poor
circulation, and air-bound zones. An air separator helps remove
entrained air from the water before it creates these problems.
5. Which component circulates water through most forced-hot-
water heating systems?
A. Expansion tank
B. Relief valve
C. Circulator pump
D. Aquastat
Rationale: The circulator pump provides the pressure differential
necessary to move heated water through the boiler, distribution
piping, radiation, and back to the boiler.
6. What is the primary purpose of a boiler aquastat?
, A. Remove sediment
B. Sense and control water temperature
C. Increase system pressure
D. Remove air from the system
Rationale: An aquastat is a temperature-sensing and control device
used with boilers. Depending on its function, it can control burner
operation, circulators, high-limit operation, or other heating-system
components.
7. Why is a low-water cutoff particularly important on a steam
boiler?
A. It increases steam pressure
B. It improves fuel efficiency
C. It helps prevent the boiler from operating without sufficient water
D. It controls room temperature
Rationale: A steam boiler can be severely damaged if the burner
operates while the boiler water level is too low. A low-water cutoff
interrupts burner operation when the water level falls below a safe
point.
8. In a steam heating system, what is the purpose of a steam trap?
Contractor Exam Questions and Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant Download
In a hydronic hot-water heating system, what is the primary function of
the expansion tank?
A. Increase boiler pressure
B. Remove dissolved oxygen
C. Absorb the increase in water volume as the water is heated
D. Increase circulation velocity
Rationale: Water expands as its temperature rises. The expansion
tank provides a compressible air or gas cushion that accommodates
this increased volume and helps prevent excessive system pressure.
, 2. What is the primary purpose of a pressure-relief valve on a
hydronic heating boiler?
A. Control the thermostat
B. Prevent low-water conditions
C. Regulate pump speed
D. Protect the boiler and piping from excessive pressure
Rationale: A pressure-relief valve is a safety device that opens
automatically when system pressure reaches its set point. This
prevents excessive pressure from damaging the boiler, piping, or other
components.
3. In a closed hot-water heating system, what component is
commonly used to maintain the minimum required system
pressure?
A. Air separator
B. Pressure-reducing fill valve
C. Circulator
D. Check valve
Rationale: A pressure-reducing fill valve automatically admits water
from the supply when system pressure falls below its regulated
setting. It helps maintain adequate pressure throughout the heating
system.
, 4. What is the main purpose of an air separator in a hydronic heating
system?
A. Increase boiler temperature
B. Reduce water pressure
C. Remove entrained air from the circulating water
D. Prevent thermal expansion
Rationale: Air in a hydronic system can cause noise, corrosion, poor
circulation, and air-bound zones. An air separator helps remove
entrained air from the water before it creates these problems.
5. Which component circulates water through most forced-hot-
water heating systems?
A. Expansion tank
B. Relief valve
C. Circulator pump
D. Aquastat
Rationale: The circulator pump provides the pressure differential
necessary to move heated water through the boiler, distribution
piping, radiation, and back to the boiler.
6. What is the primary purpose of a boiler aquastat?
, A. Remove sediment
B. Sense and control water temperature
C. Increase system pressure
D. Remove air from the system
Rationale: An aquastat is a temperature-sensing and control device
used with boilers. Depending on its function, it can control burner
operation, circulators, high-limit operation, or other heating-system
components.
7. Why is a low-water cutoff particularly important on a steam
boiler?
A. It increases steam pressure
B. It improves fuel efficiency
C. It helps prevent the boiler from operating without sufficient water
D. It controls room temperature
Rationale: A steam boiler can be severely damaged if the burner
operates while the boiler water level is too low. A low-water cutoff
interrupts burner operation when the water level falls below a safe
point.
8. In a steam heating system, what is the purpose of a steam trap?
